The present invention relates to an optical mouse chip with silicon retina structure, especially to an optical mouse chip applied to image edge abstraction and detection of moving body.
The use of a hand operated pointing device for use with a computer and its display has become almost universal. For example, an optical mouse is used in conjunction with a specific mouse pad. The recently developed mouse can operate on pad of various stuffs by image recognition skill.
FIG. 1 shows a block diagram of a prior art optical mouse chip, which comprises an image acquisition unit 1a, a digital signal processing unit 2a and a converting unit 3a. The image acquisition unit 1a captures an image corresponding to the motion of mouse and converts an analog image signal corresponding to image into a digital image signal. The digital signal processing unit 2a receives the digital image signal and manipulates the digital image signal to find the moving direction of the image and the converting unit 3a converts the moving direction of the image into PS/2 signal or quadrant signal format compatible to mouse adaptor or mouse controller.
In above-mentioned optical mouse chip, the processing unit 2a receives the digital image signal from the image acquisition unit 1a and manipulates the digital image signal to find the moving direction of the image. It is hard for the processing unit 2a to detect finer image or faster movement of image if the data amount of the image acquisition unit 1a is increased.
FIG. 2 shows the block diagram of a moving image detector, which comprises a plurality of silicon retina cells 8a. Each of the silicon retina cells 8a comprises a sensor 4a, an abstracting unit Sa, a delay unit 6a and a comparing unit 7a. The sensor 4a detects image variation to generate an analog signal and converts the analog signal to a digital signal. The abstracting unit 5a is connected to an output end of the sensor 4a and converting the digital signal to an image-moving signal. The delay unit 6a is connected to an output end of the abstracting unit 5a and delays the image-moving signal of the abstracting unit 5a. The comparing unit 7a is connected between the output end of an abstracting unit 5a in the same silicon retina cell 8a and the delay unit 6a of previous same silicon retina cell 8a to discriminate the movement of the image.
Moreover, a plurality of the silicon retina cells 8a can be grouped to synthesis a neuro network; and the moving speed and the moving direction of an image can be determined by interactive algorithm with delay and comparison operations. This interactive algorithm does not involve the processing unit 2a and the processing time is not increased with the data amount of the image acquisition unit 1a. 
However, in above-mentioned moving image detector, the delay unit 6a requires time adjustment to comply with the moving speed of image in certain condition. Moreover, binary pulses are generated along upward/downward and right/left directions to determine the moving direction of image. The moving direction of image may be incorrectly judged if binary pulses are not generated along some directions.
It is an object of the present invention to provide an optical mouse chip with silicon retina structure and having fixed delay time between adjacent scan, thus determining the moving direction of image with enhanced speed and resolution.
It is another object of the present invention to provide an optical mouse chip with silicon retina structure, which selects a largest one among a plurality of direction parameters to determine the moving direction of the image after one scanning process, thus accurately determining the moving direction of image.
It is still another object of the present invention to provide an optical mouse chip with silicon retina structure, which use bipolar transistor to find edge variation of the image.
To achieve above object, the present invention provides an optical mouse chip with silicon retina structure comprising an image sensor array, an accumulator and a comparing/selecting unit. The image sensor array is a neuro network composed of a plurality of silicon retina cells and each of the silicon retina cells sensing a direction parameter of an image along an axis. The accumulator is connected to an output end of the image sensor array and sums the direction parameters of the image along different axes. The comparing/selecting unit is connected to an output end of the accumulator and selects a largest one from the sum of direction parameters of the image along different axes to determine a moving direction of the image.
The various objects and advantages of the present invention will be more readily understood from the following detailed description when read in conjunction with the appended drawing, in which: